1. Field of the Invention
The present invention relates to devices for shifting of bicycle gears and, more particularly, to a gear-shifting device having a compact wrap spring which rotatably couples a rotary element to a notched inner housing portion.
2. Description of the Related Art
German publication DE 44 42 953 discloses a click-stop gear shift for bicycle gears. The gear shift has a notching element with notches, a detent spring having a notching projection and two projections, and a slider with different pre-bias stages for the detent spring. The two ends of the detent spring are supported by the slider, while the projection located at the center of the detent spring engages the notches in the notching element. The detent spring is arranged in an annular space of the housing. The circumferential length of this annular space exceeds that of the spring by a predetermined amount along a desired override path. This click-stop gear shift meets the following operational requirements: shifting of gears can be felt; different levels of operating force can be attained by an adjustable spring pre-bias; override paths through dead travel space exist; different rotary resistance is possible in the clockwise and counterclockwise directions by configuring the notches to have a different groove angle.